There has been known a valve timing control device for an automobile engine as disclosed in Patent Document 1 cited below. The device of Patent Document 1 has a drive plate 3 rotatably mounted on a camshaft 1 of the device and driven by the crankshaft of the engine; a driven shaft member 9 integrally mounted on the camshaft 1 and having on the periphery thereof a conversion guide 11 spaced apart at a distance from the front end of the drive plate 3; and an intermediate rotor 5 rotatably mounted on the driven shaft member 9 via a bearing 14 ahead of the conversion guide 11.
Each of the drive plate 3, driven shaft member 9, and intermediate rotor 5 is provided with radial guides 10 in the form of radial grooves, guide bores 12 skewed with respect to the circumference, a spiral guide 15, and balls 16 that can roll in the guides (10, 12, 15). The intermediate rotor 5 is rotated relative to the driven shaft member 9 as the yoke 19 integrated with the intermediate rotor 5 is driven by magnetic forces exerted by electromagnetic coils 22a and 22b. 
In the device of Patent Document 1, as the intermediate rotor 5 is rotated relative to the driven shaft member 9 by magnetic forces in the phase retarding direction, the balls 16 roll in the spiral guide 15 and is displaced radially inwardly in the respective radial guides 10, thereby performing a cam action on the conversion guide 11, which in turn causes the driven shaft member 9 integral with the camshaft 1 to be advanced in phase relative to the drive plate 3. On the other hand, as the intermediate rotor 5 is rotated in the phase advancing direction relative to the driven shaft member 9 under the magnetic forces, the balls 16 roll in the respective guides 15, 10, and 11 in the opposite direction, performing a cam action on the conversion guide 11 in the opposite direction to retard the phase of the driven shaft member 9 relative to the drive plate 3.